The Pilot Study Of Several Factors Effects On The Tension Of Rat Isolated Aortic Rings

Sulfur dioxide, as a major air pollutant, has been paid more and more attention to its toxic effect. Recently, many studies have indicated that SO₂ is a system toxin, and inhalation SO₂ or celiac injection SO₂ derivatives on rat lead to lower significantly blood pressure. Now, as antiseptic and additive , hydrogen peroxide is used in our diet; because of the changes of diet and environment, the population of acidity corporeity has been increasing, it is harmful to our body; KCl is used in many ways, research about the relation of KCl and hypertension had been done, however, the results are not consistent. In this study, the pathway and mechanism on lowering the blood pressure of SO₂ derivatives were studied in the following aspects; effects of pH,H₂O₂ and KCl on the rat isolated aortic rings tension were also studied in the following aspects:1. Changes in cyclic nucleotides, TXA₂ and PGI₂ metabolism after rat vasodilatation caused by SO₂ derivatives and their significanceLevels of cAMP, cGMP, 6-Keto-PGF_1α , TXB₂ in the isolated aortic rings of rats were determined by radioimmunoassay. Our results indicated that (1)SO₂ derivatives could dose-dependently relax the isolated aorta rings with or without endothelium precontracted by NE, no difference was found for the rings with and without endothelium;(2)Levels of cAMP and 6-Keto(PGI₂) in isolated aortic rings were increased by SO₂ derivatives in a dose-dependent way, which were independent of endothelium;(3)SO₂ derivatives decreased cGMP levels in the rings, but not significantly; The decrease of cGMP levels was also independent of endothelium;(4)No changes of TXB₂ in rings with or without endothelium were observed;(5)Whether presence or absence of endothelium, cAMP/cGMP and 6-Keto/TXB₂ ratios were increased significantly. These results led to the conclusions that(1)SO₂ derivatives had endothelium-independent effect of relaxation on rat aorta rings. (2)SO₂ derivatives caused a increase of PGI₂, and cAMP might attach itself to signal transduction pathway.2.effects of pH on the tension of isolated aortic rings of ratlevels of NO and sulfite were respectively determined by nitric acid reductase and high-performance liquid chromatographic(HPLC) method. Our results indicated that (1) aortic rings with and without endothelium precontracted by NE to decreased pH induced a relaxation; aortic rings with and without endothelium to increased pH induced a contraction; there is no significant difference in presence and absence of endothelium . (2)NO levels had no significant change in isolated aortic rings presence and absence of endothelium to decreased pH and increased pH ; (3)sulfite levels in isolated aortic rings with endothelium reduced to decreased pH and increased pH. sulfite levels in aortic rings without endothelium had no remarkable change. These results led to the conclusions that (1)pH had endothelium-independent effect of relaxation and contraction on rat aorta rings; (2)NO probably had no effects of relaxation and contraction on rat aorta rings; (3)sulfite levels in isolated aortic rings presence of endothelium reduced to decreased pH and increased pH, the change of sulfite levels are likely to affect the relaxation and contraction of rat blood vessel.3. effects of H₂O₂ on the tension of isolated aortic rings of ratAs above methods,Our results indicated that (1) aortic rings with endothelium precontracted by NE to 10000μmol/L H₂O₂ induced a relaxation; aortic rings with endothelium to 100μmol/L H₂O₂ induced a significant contraction;H₂O₂ induced the same effects in aortic rings without endothelium, there is significant difference in presence and absence of endothelium.(2)10000μmol/L H₂O₂ could increase NO levels and 100μmol/L H₂O₂ could reduce NO levels in isolated aortic rings with and without endothelium;there is significant difference in presence and absence of endothelium. (3) sulfite levels in isolated aortic rings with endothelium multiplied to 10000μmol/L H₂O₂ and reduced to 100μmol/L H₂O₂. sulfite levels in aortic rings without endothelium had no remarkable change. These results led to the conclusions that(1)H₂O₂ had endothelium-dependent effect of relaxation and contraction on rat aorta rings;(2)NO probably had effect of relaxation and contraction induced by H₂O₂ on rat aorta rings; (3)the change of sulfite levels are likely to affect the relaxation and contraction induced by H₂O₂ of rat blood vessel.4. effects of KCl on the tension of isolated aortic rings of ratAs above methods,Our results indicated that(1)aortic rings presence and absence of endothelium to KCl induced a concentration dependent contraction; there are no significant difference in presence and absence of endothelium. (2)NO levels had no significant change in isolated aortic rings presence of endothelium to KCl; however, NO levels decreased in absence of endothelium, there are significant difference in presence and absence of endothelium.(3)sulfite levels in isolated aortic rings presence of endothelium had no significant change to KCl, sulfite levels in aortic rings absence of endothelium had a remarkably increase, there are significant difference in presence and absence of endothelium. These results led to the conclusions that(1)KCl had endothelium-dependent effect of contraction on rat aorta rings; (2)NO probably had no effect of contraction induced by KCl on rat aorta rings; (3)the change of sulfite levels are likely to affect the contraction of rat blood vessel.